Ink set, ink container, inkjet recording method, recording device, and recorded matter

ABSTRACT

An ink set, comprising: an oil based ink composition containing a metallic pigment; and at least one or more oil based ink compositions selected from a group consisting of a chromatic color ink composition containing chromatic color pigment, a black ink composition containing black pigment, and a white ink composition containing white pigment.

This application claims priority from Japanese Patent Application No.2007-017276, filed on Jan. 29, 2007, and from Japanese PatentApplication No. 2007-263801, filed on Oct. 9, 2007, the contents ofwhich are incorporated herein.

BACKGROUND

1. Technical Field

The present invention relates to an ink set, ink container, inkjetrecording method, recording device, and recorded matter, andparticularly relates to an ink set, ink container, inkjet recordingmethod, recording device, and recorded matter, which can form a filmwith metallic gloss.

2. Related Art

Conventionally, gold bronze powder made of brass and aluminum finepowder and the like, printing ink with silver powder pigment, foil pressprinting using metal foil, and a thermal transfer method using a metalfoil have been used to form a film with metallic gloss on printedmatter.

However, with a coating film consisting of a printing ink that uses goldbronze powder, or silver powder, the average particle size of the metalpowders that are used will be large, between 10 μm and 30 μm, and thus aflat metallic finish can be obtained, but achieving a mirror surfacegloss is difficult. Furthermore, with the foil press or thermal transfermethods that use a metallic foil, an adhesive is applied as a printingcarrier, and a flat metallic foil is pressed thereon, the recordingcarrier and the metallic foil are heated to cause firm adhesion, and themetal foil and recording carrier are thermally fused together.Therefore, a relatively good gloss can be achieved, but there are manymanufacturing steps, and pressure and heat are applied during themanufacturing process, so the recording medium is restricted by thelimited recording media that are resistant to heat and deformation.

In recent years, many examples of applying inkjet technology to printinghave been seen, and one example of application is metallic printing. Forexample, JP-A-2002-179960 discloses technology of forming a metal filmon a plastic spherical particle surface, and printing an ink compositionthat contains a pigment using inkjet printing. However, in order toobtain a highly metallic gloss, the spheres must be deformed andflattened to make a smooth surface, and with this technology, heatingand pressing with a roller must be simultaneously performed. Therefore,the equipment and manufacturing processes are inevitably complicated bythis point, and the recording medium is also restricted.

Furthermore, JP-A-2003-292836 and JP-A-2003-306625 disclose technologythat uses an ink composition wherein a colloid of a precious metal suchas gold or silver is dispersed. However, if the particle size of theprecious metal colloid is small, within a range between severalnanometers and several tens of nanometers in order to give priority todispersion stability, discoloration caused by plasmon absorption willoccur, and the ink composition will not provide a metallic gloss. Inthis case, after the coating film is dried, a metallic gloss is achievedby heating to 150° C. or higher in order to fuse the colloid particlestogether. Furthermore, if the particle size is increased in order togive priority to metallic gloss, the dispersion stability will bedegraded, and problems with conglomeration and settling will beinevitable, and the storage life of the ink composition will besignificantly reduced. Furthermore, although trivial, using preciousmetals as a material will increase the cost of the ink composition, souse will be restricted to applications with high added value, and thereare disadvantages related to cost.

Furthermore, a metallic ink composition is known which uses a blend ofmetallic pigment and colorant as one ink composition, but when printingwith this method, there are problems with the metallic pigment and thecolorant separating and only the metallic pigment settling duringstorage of the ink composition, and this is a cause of printing defectssuch as the creation of a nonuniform image with variation and color lossoccurring because only the colorant is absorbed into the recordingmedium leaving only the metallic pigment on the surface.

SUMMARY

An advantage of an aspects of the present invention is the ability toprovide an ink set capable of forming a coating film with a metallicgloss of any color on printed matter using aluminum as a relativelyinexpensive metallic material, and making the ink set of inkcompositions which have high metallic mirror surface gloss.

As result of diligent research, the present inventors have discoveredthat printed matter with a high mirror surface gloss which washeretofore unattainable can be obtained by using a metal pigmentdispersion, ink composition, inkjet recording method, and recordedmatter that uses specific metal pigments. The present invention is basedon these findings, and provides the following inventions.

[1] An ink set, containing an oil based ink composition containing ametallic pigment, and at least one or more oil based ink compositionsselected from a group consisting of chromatic color ink compositioncontaining chromatic color pigment, a black ink composition containingblack pigment, and a white ink composition containing white pigment.

Preferred aspects of the invention are as shown below.

[2] The ink set according to [1], wherein the metallic pigment is aplate-like particle, where, on a planar surface of the plate-likeparticle if a longitudinal diameter is X, a lateral diameter is Y, and athickness is Z, a 50% average particle diameter R50 which is thediameter of a corresponding circle determined by a surface area in theX-Y plane of the plate-like particle is between 0.5 and 3 μm, andR50/Z>5 is satisfied;

[3] The ink set according to [1], wherein the metal pigment is aluminumor an aluminum alloy;

[4] The ink set according to [1], wherein the metal pigment is made bycrushing a metal deposition film;

[5] The ink set according to [1], wherein an oil based ink compositioncontaining the metallic pigment contains the metallic pigment, anorganic solvent, and a resin;

[6] The ink set according to [1], wherein concentration of the pigmentin the oil based ink composition is between 0.1 and 10.0 wt %;

[7] The ink set according to [5], wherein the organic solvent includesone or more type of alkylene glycol ether that is a liquid at ambienttemperature and pressure;

[8] The ink set according to [5], wherein the organic solvent is amixture of an alkylene glycol diether, an alkylene glycol monoether, anda lactone;

[9] The ink set according to [5], wherein the resin is at least one typeof resin selected from a group consisting of polyvinyl butyral,cellulose acetatobutyrate, and polyacryl polyol, polyurethane,vinylchloride-vinylacetate copolymer and/or a resin emulsion thereof;

[10] The ink set according to [5], wherein the oil based ink compositionfurther has at least one type of acetylene glycol based surfactantand/or silicone based surfactant;

[11] The ink set according to [1], wherein the chromatic color pigmentis an organic pigment, the black pigment is carbon black, and the whitepigment is titanium dioxide and/or a hollow resin emulsion;

[12] An ink container containing the ink set according to any one of [1]through [11];

[13] An inkjet recording method, having: ejecting droplets of inkcomposition, and causing the droplets to adhere to a recording medium,an image being formed using the ink set according to any one of [1]through [11];

[14] The ink jet recording method according to [13], having: forming animage by simultaneously ejecting the oil based ink compositioncontaining metallic pigment, and at least one type of compositionselected from a group consisting of a chromatic color ink composition, ablack ink composition, and a white ink composition;

[15] The inkjet recording method according to [13], having: forming animage using the oil based ink composition containing a metallic pigment,and then forming an image of any color using the chromatic color inkcomposition;

[16] The inkjet recording method according to [13], having: forming animage using the oil based ink composition containing a metallic pigment,then forming an image of any color using the chromatic color inkcomposition, and then forming an image using the black ink compositionand/or the white ink composition;

[17] The inkjet recording method according to [13], wherein the methodof ejecting the ink composition is a non-heating method;

[18] The inkjet recording method according to [13], wherein therecording medium is heated and printed;

[19] The inkjet recording method according to [18], wherein the heatingtemperature is between 30° C. and 80° C.;

[20] The inkjet recording method according to [19], wherein the heatingis performed prior to printing and/or during printing and/or afterprinting;

[21] An inkjet recording ejecting droplets of ink composition, andcausing the droplets to adhere to a recording medium, an image beingformed using the ink set according to any one of [1] through [11]; and

[22] Recorded matter, recorded using the inkjet printing methodaccording to any one of [13] through [20] and the recording deviceaccording to [21].

Using the ink set, inkjet recording method, and recorded matter of thepresent invention, an image with high metallic gloss can be formed on arecording medium using an ink composition containing metallic pigment,and furthermore, an image with metallic gloss of any arbitrary color andimages which were not obtainable with a conventional ink set can beformed using an ink set which combines a chromatic color inkcomposition, a black ink composition, and a white ink composition.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Ink Set

a. As described above, the ink set according to one aspect of theinvention contains an oil based ink composition containing a metallicpigment; and at least one or more oil based ink compositions selectedfrom a group consisting of a chromatic color ink composition containingchromatic color pigment, a black ink composition containing blackpigment, and a white ink composition containing white pigment. Thereby,an image can be formed with a metallic gloss that is colored bychromatic color pigment, black pigment, and white pigment.

The metallic pigment is preferably a plate-like particle, where, on theplanar surface of the plate-like particle, the longitudinal diameter isX, the lateral diameter is Y, and the thickness is Z, the 50% averageparticle diameter R50 which is the diameter of a corresponding circledetermined by the surface area in the X-Y plane of the plate-likeparticle is between 0.5 and 3 μm, and R50/Z>5 is satisfied.

The term “plate-like particle” refers to particles which haveessentially a flat surface (X-Y plane) and essentially a uniformthickness (Z). The plate-like particles are made by crushing a metaldeposition film, and therefore metal particles with essentially a flatsurface and essentially a uniform thickness can be obtained.Furthermore, the longitudinal diameter, lateral diameter, and thicknessof the plate-like particle can be defined as X, Y, and Z respectively.

The term “diameter of a corresponding circle” refers to the diameter ofan imaginary circle which has the same projected surface area as theprojected surface area on the essentially flat surface (X-Y plane) ofthe plate-like particles of the metallic pigment. For example, if theessentially flat surface (X-Y plane) of the plate-like particles of themetallic pigment is polygonal, the diameter of the corresponding circleof the plate-like particle of metallic pigment is the diameter of thecircle obtained by converting the projected area of that polygon to acircle.

The 50% average particle diameter R50 of a corresponding circledetermined using the surface area of the X-Y plane of the plate-likeparticles is preferably between 0.5 and 3 μm, and more preferablybetween 0.75 and 2 μm, from the perspective of metallic gloss andprinting stability.

Furthermore, the relationship between the 50% average particle diameterR50 of a corresponding circle and the thickness Z is preferably suchthat R50/Z>5, from the perspective of ensuring high metal gloss.

The metallic pigment is preferably aluminum or an aluminum alloy, from aperspective of cost and a perspective of ensuring metal gloss. If analuminum alloy is used, the other metal elements or non-metal elementsthat can be added to the aluminum are not particularly restricted solong as the element has metallic gloss, but silver, gold, platinum,nickel, chrome, tin, zinc, indium, titanium, and copper and the like canbe suggested, and these elements can be favorably used individually, oras an alloy, or as a mixture of at least one type of element.

The method of manufacturing the metallic pigment is to peel theinterface between a metal or alloy layer and a peeling resin layer froma sheet substrate of a composite pigment source with a structure where apeeling resin layer and a metal or alloy layer is successively overlaidonto a sheet substrate surface, followed by crushing and pulverizing toobtain plate-like particles. Furthermore, for the case where thelongitudinal diameter of the planar surface of the plate-like particleis X, the lateral diameter is Y, and the thickness is Z, the 50% averageparticle diameter R50 which is the diameter of a corresponding circledetermined by the surface area in the X-Y plane of the plate-likeparticle obtained is between 0.5 and 3 μm, and the condition R50/Z isless than 5.

The longitudinal diameter X, lateral diameter Y, and the diameter of acorresponding circle on the surface of the metallic pigment (plate-likeparticle) can be measured using a particle image analyzer. For example,a flow type particle image analyzer FPIA-2100, FPIA-3000, or FPIA-3000Smanufactured by Sysmex Corporation can be used as a the particle imageanalyzer.

The metal or alloy layer is preferably made using vacuum deposition, ionplating, or sputtering.

The thickness of the metal or metal alloy is 20 nm or higher and 100 nmor less. Thereby a pigment with an average thickness of 20 nm or higherand 100 nm or less can be obtained. If the average thickness is 20 nm orgreater, the pigment will have excellent reflectivity and brightness,and will have good properties as a metallic pigment, and if the averagethickness is 100 nm or less, an increase in the apparent specificgravity can be suppressed and stability in metallic pigment dispersioncan be obtained.

The peeling resin layer of the composite pigments source is an undercoatlayer under the metal or alloy layer, and is a peeling layer forincreasing the peeling properties to the sheet substrate surface. Theresin that is used as the resin peeling layer is preferably a polyvinylalcohol, polyvinyl butyral, polyethylene glycol, polyacrylic acid,polyacrylamide, cellulose derivative, acrylic acid polymer, or modifiednylon resin.

A solution containing a mixture of one or more of the aforementionedresins is applied to the recording medium, and a layer is formed bydrying or the like. After applying, the resin can contain an additivesuch as a viscosity adjusting agent.

The peeling resin layer can be formed using commonly used gravureapplication, roller application, blade application, extrusionapplication, dip application, or spin coat method or the like. Afterapplying and drying, the surface can be smoothed by calendaring ifnecessary.

The thickness of the peeling resin layer is not particularly restricted,but is preferably between 0.5 and 50 μm, more preferably between 1 and10 μm. If the thickness is less than 0.5 μm, the amount of dispersionresin will be insufficient, and if the thickness is greater than 50 μm,peeling at the interface with the pigment layer will readily occur whenrolled.

The sheet substrate is not particularly restricted, but can be apolyester film such as polytetrafluoroethylene, polyethylene,polypropylene, and polyethylene terephthalate, a polyamide film such as66-nylon and 6-nylon, or a peeling film such as a polycarbonate film,triacetate film, or polyimide film, or the like. Preferably, the sheetsubstrate is made of polyethylene terephthalate or a copolymer thereof.

The thickness of the sheet substrate is not particularly restricted, butis preferably between 10 and 150 μm. If the thickness is 10 μm orgreater, handling problems such as processing will not occur, and if thethickness is 150 μm or less, the flexibility will be excellent, andproblems will not occur when rolled or peeled or the like.

Furthermore, the metal or alloy layer can be enclosed between protectivelayers as shown in JP-A-2005-68250. The protective layer can be asilicon oxide layer or a protective resin layer.

The silicon oxide layer is not particularly restricted so long as thelayer contains silicon oxide, but is preferably formed from a siliconalkoxide such as tetralkoxysilane, or polymer thereof.

The silicon oxide layer film is formed by applying a solution of siliconalkoxide or polymer thereof dissolved in alcohol, and then baking.

The protective resin layer is not particularly restricted so long as theresin does not dissolve in the dispersion solvent, and examples includepolyvinyl alcohol, polyethylene glycol, polyacrylic acid,polyacrylamide, or a cellulose derivative, and is preferably a polyvinylalcohol or a cellulose derivative.

An aqueous solution containing a mixture of one or more of theaforementioned resins is applied, and a layer is formed by drying or thelike. The application solution can contain an additive such as aviscosity adjusting agent.

Application of the silicon oxide and resin is performed by the samemethod as application of the peeling resin layer.

The thickness of the protective layer is not particularly restricted,but is preferably in a range between 50 and 150 nm. If the thickness isless than 50 nm, the mechanical strength will be insufficient, but ifthe thickness exceeds 150 nm, the strength will be too high, so crushingand dispersing will be difficult, and peeling will occur at theinterface with the metal or alloy layer.

Furthermore, a layer of colored material can be placed between the“protective layer” and the “metal or alloy layer.”

The colored layer is added to obtain a composite pigment of any color,and the materials are not particularly restricted so long as the coloredmaterial can provide an arbitrary color or hue, in addition to the metalgloss and brightness of the metallic pigment of the invention. Thecolored material used in the colored layer can be either a pigment ordye. Furthermore, any commonly used pigment or dye can be suitably used.

In this case, the “pigment” that is used in the colored layer refers toa natural pigment, synthetic organic pigment, or synthetic inorganicpigment or the like as generally defined in the field of pigmentchemistry, and is different than the “compound pigment” of the presentinvention formed with a multilayer structure.

The method of forming the colored layer is not particularly restricted,but is preferably formed by coating.

Furthermore, if the colorant that is used in the colored layer is apigment, a resin for dispersing the colorant is preferably included, andthe resin for dispersing the colorant is preferably made by dispersingor dissolving a pigment, a resin for dispersing the colorant, and otheradditives if necessary, in a solvent, forming a uniform liquid layer bycoating this solution, and then drying to make a thin resin film.

Note, when manufacturing the composite pigment source, both the colorantlayer and the protective layer are preferably formed by coating in orderto improve productivity.

The composite pigment source may also have a layered construction with aplurality of multilayered structures of successive peeling resin layers,and metal or alloy layers. At this time, the total thickness of themultilayer structure containing a metal or alloy layer, or in otherwords the thickness of metal or alloy—peeling resin layer—metal or alloylayer, or the peeling resin layer—metal or alloy layer is preferably5000 nm or less. If the thickness is 5000 nm or less, cracking andpeeling will not occur even if the composite pigment source is rolledup, and storage properties will be excellent. Furthermore, when apigment is formed, the pigment will be favorable, with excellentbrightness.

Furthermore, a structure containing multiple successive layering of apeeling resin layer and a metal or an alloy layer on both sides of thesheet substrate surface can be suggested, but this is not a restriction.

The method of peeling from the sheet substrate is not particularlyrestricted, but a method of immersing the composite pigment source in aliquid, or a method of immersing in a liquid while simultaneouslyapplying ultrasonic waves, peeling, and then crushing the peeledcomposite pigment are preferable.

With the pigment obtained as described above, the peeling resin layeralso acts as a protective colloid, and therefore a stable dispersion canbe obtained simply by dispersing in a solvent. Furthermore, with the inkcomposition that uses this pigment, the resin derived from the peelingresin layer also functions to provide adhesion to the recording medium,such as paper.

The oil based ink composition used in the ink set of this embodimentcontains the aforementioned metallic pigment, organic solvent, andresin.

The concentration of the metallic pigment in the ink composition ispreferably between 0.1 and 10.0 wt %.

If the concentration of metallic pigment in the ink composition is 0.1wt % or higher and less than 1.5 wt %, a half mirror gloss surface, orin other words a glossy feel can be achieved by ejecting an amount ofink that does not sufficiently cover the printing surface, but printingon a texture where the background appears to be transparent will bepossible, and a metal glossy surface with high gloss can be formed byejecting sufficient ink to cover the printing surface. Therefore, thisis suitable for forming a half mirror image on a transparent recordingmedium, or for providing a metal gloss surface with high gloss.Furthermore, if the concentration of metallic pigment in the inkcomposition is 1.5 wt % or higher and 3.0 wt % or lower, the metalpigment will be randomly arranged on the printing surface, so a highgloss will not be achieved and a metal gloss surface with a matte finishcan be formed. Therefore, this is suitable for forming a shielding layeron a transparent recording medium.

The organic solvent is preferably a polar organic solvent, and examplesinclude alcohols (such as methyl alcohol, ethyl alcohol, propyl alcohol,butyl alcohol, isopropyl alcohol, or fluorodated alcohol and the like),ketones (such as acetone, methylethyl ketone, and cyclohexanone and thelike), carboxylate esters (such as methyl acetate, ethyl acetate, propylacetate, butyl acetate, methyl propionate, and ethyl propionate and thelike), and ethers (such as diethyl ether, dipropyl ether,tetrahydrofuran, and dioxane, and the like).

In particular, the organic solvent preferably contains one or more typeof an alkylene glycol ether that is a liquid at ambient temperature andpressure.

The alkylene glycol ether can be an ethylene glycol based ether orpropylene glycol based ether which contains a methyl, n-propyl,i-propyl, n-butyl, i-butyl, hexyl, or 2-ethyl hexyl resin group and anallyl or phenyl group having a double bond as a base. These alkyleneglycol ethers are colorless with little odor, and have an ether groupand a hydroxyl group in the molecule, and therefore demonstrate theproperties of both alcohols and ethers, and are liquid at roomtemperature. Furthermore, these alkylene glycol ethers can be monoetherswhere only one of the hydroxyl groups has been substituted, or can bediethers, where both of the hydroxyl groups have been substituted, andfurthermore a plurality of types can be combined and used together.

In particular, the organic solvent is preferably a blend of an alkyleneglycol diether, an alkylene glycol monoether, and a lactone.

Examples of the alkylene glycol monoether include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, ethylene glycolmonoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycolmonohexyl ether, ethylene glycol monophenyl ether, diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, diethylene glycol dimethyl ether, diethylene glycoldiethyl ether, triethylene glycol monomethyl ether,triethylene glycolmonoethyl ether, triethylene glycol monobutyl ether, tetraethyleneglycol monomethyl ether, etraethylene glycol monoethyl ether, propyleneglycol monomethyl ether, propylene glycol monoethyl ether, dipropyleneglycol monomethyl ether, dipropylene glycol monoethyl ether, and thelike.

Examples of alkylene glycol diethers include ethylene glycol dimethylether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, triethylene glycol dimethyl ether,triethylene glycol diethyl ether, triethylene glycol dibutyl ether,tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether,tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether,propylene glycol diethyl ether, dipropylene glycol dimethyl ether,dipropylene glycol diethyl ether, and the like.

Furthermore, the lactone can be γ-butyrolactone, δ-valerolactone, andε-caprolactone and the like.

The objective of the present invention can be better achieved by usingone of the aforementioned favorable constructions.

The resin that is used in the oil based ink composition is for examplean acrylic resin, a styrene-acrylic resin, a rosin modified resin, aterpene based resin, a polyester resin, a polyamide resin, an epoxyresin, a vinylchloride resin, a vinylchloride-vinylacetate copolymer, afiber based resin (such as cellulose acetate buterate, hydroxypropylcellulose), polyvinyl butyral, polyacryl polyol, polyvinyl alcohol, andpolyurethane and the like.

Furthermore, fine particles of a nonaqueous dispersion polymer can alsobe used as the resin. These are dispersions where fine particles ofpolyurethane resin, acrylic resin, acrylpolyol resin or the like arestably dispersed in an organic solvent. Examples include polyurethaneresins such as “Sanprene IB-501” and “Sanprene IB-F370”, manufactured bySanyo Chemical Industries, Ltd., and acrylicpolyol resins such as“N-2043-60MEX” and “N-2043-AF-1” manufactured by Harima Chemicals, Inc.

The amount of resin emulsion added to the ink composition is preferably0.1 wt % or higher and 10 wt % or lower, in order to further increasethe adhesion of the pigment to the recording medium. If the amount addedis excessive, printing stability will not be achieved, but ifinsufficient, adhesion will be insufficient.

The ink composition preferably contains at least one type of glycerin,polyalkylene glycol, or sugar. The amount of at least one type ofglycerin, polyalkylene glycol, or sugar that is added to the inkcomposition is preferably 0.1 wt % or higher and 10 wt % or lower.

With this type of preferred construction, drying of the ink can besuppressed, plugging can be prevented, ejection of the ink can bestabilized, and the image quality of the recorded matter can befavorable.

The polyalkylene glycol is a linear polymer compound with a constructionof repeating ether bonds in the main chain, and is produced for exampleby ring opening polymerization of a cyclic ether.

Specific examples of polyalkylene glycol include polymers such aspolyethylene glycol and polypropylene glycol, ethylene oxide-propyleneoxide copolymer and derivatives thereof. The copolymer can be any typeof copolymer such as a random copolymer, block copolymer, graftcopolymer, or alternating copolymer.

Preferable examples of a polyalkylene glycol include goes expressed bythe following formula.

HO—(CnH₂nO)m-H

(In the above formula, n represents an integer between 1 and 5, and mrepresents an integer between 1 and 100.)

Note, in the formula, (CnH₂nO)m can have a single value for n or canhave a combination of two or more values within the range of integer n.For example, the term becomes (C₃H₆O)m if n is 3, or becomes(CH₂O—C₄H₈O)m if n is a combination of 1 and 4. Furthermore, the integerm can be a single constant or a combination of two or more constantswithin the aforementioned range. For instance, in the above example, ifm is a combination of 20 and 40, the term becomes (CH₂O)₂₀—(C₂H₄O)₄₀,and if m is a combination of 10 and 30, the termbecomes(CH₂O)₁₀—(C₄H₈O)₃₀. Furthermore, the integers n and m can be inany combination with in the aforementioned ranges.

The sugar can be a simple sugar such as pentose, hexose, heptose,octose, a polysaccharide such as a disaccharide, trisaccharide, ortetrasaccharide, as well as derivatives thereof such as sugar alcohols,reduced derivatives such as deoxy acids, oxidized derivatives such asaldonic acid and uronic acid, dehydrated derivatives such as glycocine,as well as amino acids and thiosugars and the like. Polysaccharidesrepresent a wide range of saccharides, and include substances widelyfound in nature such as alginic acid, dextrin, and cellulose.

The oil based ink composition preferably contains at least one type ofacetylene glycol based surfactant and/or silicone based surfactant. Theamount of surfactant added is preferably 0.01 wt % or higher and 10 wt %or lower, based on the amount of pigment in the ink composition.

With this preferred composition, the wettability of the oil based inkcomposition towards the recording medium will be improved, and rapidadhesion can be achieved.

Preferred examples of the acetylene glycol based surfactant includeSurfinol 465 (trademark), Surfinol 104 (trademark) (product trade names,manufactured by Air Products and Chemicals Inc.), Olfin STG (trademark),Olfin E1010 (trademark) (product trade names, manufactured by NissinChemical Industry Co., Ltd.), and the like.

Preferred examples of the silicone surfactant include polyester modifiedsilicone and polyether modified silicone. Specific examples includeBYK-347, BYK-348, BYK-UV3500, BYK-UV3510, BYK-UV3530, and BYK-UV3570(manufactured by BYK Chemie Japan).

The oil based ink composition can be prepared by a commonly known andused method. For example, the aforementioned metallic pigment,dispersing agent, and solvent are first blended together and then apigment dispersion is prepared using a bowl mill, bead mill, ultrasonicwaves, or jet mill or the like, in order to achieve the desired inkcharacteristics. Furthermore, a pigment ink composition can be obtainedby adding a binder resin, solvent, and other additives (such asdispersion assisting agents and viscosity adjusting agents) whilemixing.

In addition, the composite pigment source is ultrasonically treated in asolvent to make a composite pigment dispersion, and then the necessaryink solvents can be blended, or the composite pigment source can beultrasonically treated in the ink solvent to directly make the inkcomposition.

The physical properties of the oil based ink composition are notparticularly restricted, but for example the surface tension ispreferably between 20 and 50 mN/m. If the surface tension is less than20 mN/m, the ink composition will spread out on the surface of theinkjet recording printer head, or will smear, and ejection of inkdroplets will be difficult. On the other hand, if the surface tensionexceeds 50 mN/m, the ink composition will not spread out on the surfaceof the recording medium, and favorable printing will not be possible.

Next, the chromatic color ink compositions, black ink compositions, andwhite ink compositions that are used in the ink set of this aspect willbe described.

The chromatic color ink composition contains a chromatic color pigment.The term “colored” refers to any color other than achromatic colors fromwhite through gray to black. The chromatic color pigments are preferablyorganic pigments, from the perspective of storage stability such aslightfastness, weatherfastness, and gasfastness.

Specific examples include azo pigments such as insoluble azo pigments,condensed azo pigments, azo lake, and chelated azo pigments; polycyclicpigments such as phthalocyanine pigments, perylene and perinonepigments, anthraquinone pigments, quinacridone pigments, dioxanepigments, thioindigo pigments, isoindolinone pigments, andquinophthalone pigments; as well as dye chelates (for example basic dyechelates, acidic dye chelates, and the like), dye lakes (basic dyelakes, acidic dye lakes), nitro pigments, nitroso pigments, anilineblack, and daylight fluorescent pigments and the like. These pigmentscan be used independently, or used as a combination of two or more. Morespecific examples include C. I. Pigment yellow 1 (fast yellow G), 2, 3,12 (diazo yellow AAA), 13, 14, 16, 17, 24, 34, 35, 37, 42 (yellow ironoxide), 53, 55, 73, 74, 75, 81, 83 (dis-azo yellow HR), 93, 94, 95, 97,98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 129, 138, 139, 150,153, 154, 155, 180, 185, 213, C. I. Pigment red 1, 2, 3, 5, 7, 17, 22(brilliant fast scarlet), 23, 31, 38, 48:2 (permanent red 2B(Ba)), 48:2(permanent red 2B(Ca)), 48:3 (permanent red 2B(Sr)), 48:4 (permanent red2B(Mn)), 49:1, 52:2, 53:1, 57:1 (brilliant carmine 6B), 60:1, 63:1,63:2, 64:1, 81 (rhodamine 6G lake), 83, 88, 101 (bengara), 104, 105,106, 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170,172, 177, 178, 179, 184, 185, 190, 193, 202, 209, 219, C. I. Pigmentviolet 19, C. I. Pigment blue 1, 2, 15 (phthalocyanine blue R), 15:1,15:2, 15:3 (phthalocyanine blue G), 15:4, 15:6 (phthalocyanine blue E),16, 17:1, 22, 56, 60, 63, C. I. Pigment green 1, 4, 7, 8, 10, 17, 18,36, and the like.

Note, even pigments which are not shown in the color index can be usedso long as the pigment is water insoluble.

The black ink composition contains a black pigment. Examples of blackpigments include furnace black, lamp black, acetylene black, channelblack, and other carbon blacks (C. I. Pigement black 7), as well ascopper oxides, iron oxide (C. I. Pigment black 11), and other metals,aniline black (C. I. Pigment black 1) and other organic pigments, butcarbon black pigments which have a relatively low specific weight and donot easily settle out in water are preferable for inkjet use. Thesepigments can be used individually or as a blend of two or more.

The white ink composition contains a white pigment. Examples of whitepigments include titanium dioxide, zirconium dioxide, and other periodictable group IV element oxides. In addition, calcium carbonate, calciumsulfate, zinc oxide, barium sulfate, barium carbonate, silica, alumina,kaolin, clay, talc, white clay, aluminum hydroxide, magnesium carbonate,and white hollow resin emulsion and the like, and preferably a blend ofone or more types selected from a group consisting of these pigments isused.

A hollow resin emulsion refers to an oil based dispersion that containsfine hollow polymer particles, wherein the fine hollow polymer particlesconsist of subgroups of a plurality of fine particles, and with regardsto the average particle size, the difference in the average particlesize of adjacent fine particle subgroups is less than 100 nm.

The primary particle size of the aforementioned white pigment ispreferably less than 1 μm, from the perspective of whiteness.

Herein, the term “primary particle size” refers to the size of aparticle formed by conglomerating individual crystals or similar crystalparticles. The primary particle size is measured using an electronmicroscope method. This method measures the size of the pigment particlefrom an electron microscope photograph, and a more reliable value can bedetermined by dispersing the pigment in an organic solvent, fixing on asupport film, performing image processing from a transmission typeelectron microscope photograph, and measuring. Specifically, thelongitudinal diameter and the lateral diameter of each of the primaryparticles is measured, the diameter of the circle of the equal surfacearea is calculated and used as the primary particle size, and theaverage value of 50 or more randomly selected pigment particles from afixed view is determined. Other measurement methods can also be used solong as equivalent reliability can be achieved, but if there is asignificant difference in the values, the values determined by theaforementioned method are used.

The chromatic color ink composition and the black ink composition can beappropriately determined, but the amount of pigment in the inkcomposition is between 0.1 and 30 wt %, preferably between 0.5 and 12 wt%. The amount of pigment in the white ink composition is preferably 1.0wt % or higher, more preferably at 5.0 wt % or higher, and even morepreferably 10 wt % or higher but 20 wt % or less, from the perspectiveof whiteness.

The ink composition that is used in the ink set of this aspect uses apigment as a colorant, and preferably contains a dispersing agent inorder to disperse the pigment. The dispersing agent can be used withoutrestriction, so long as the dispersing agent can be used in a pigmentink, and examples include cationic dispersing agents, anionic dispersingagent nonionic dispersing agents and surfactants and the like.

Examples of anionic dispersing agents include polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer,vinylacetate-acrylic acid ester copolymer, acrylic acid-alkyl acrylateester copolymer, styrene-acrylic acid copolymer, styrene-methacrylicacid copolymer, styrene-acrylic acid-alkyl acrylate ester copolymer,styrene-methacrylic acid-alkyl acrylate ester copolymer,styrene-α-methylstyrene-acrylic acid copolymer,styrene-α-methylstyrene-acrylic acid-alkyl acrylate ester copolymer,styrene-maleic acid copolymer, vinylnaphthalene-maleic acid copolymer,vinylacetate-ethylene copolymer, vinylacetate-fatty acid vinylethylenecopolymer, vinylacetate-maleic acid ester copolymer,vinylacetate-crotonic acid copolymer, and vinylacetate-acrylic acidcopolymer and the like.

Examples of nonionic dispersing agents include polyvinyl pyrrolidone,polypropylene glycol, and vinylpyrrolidone-vinylacetate copolymer, andthe like.

Examples of surfactant as dispersing agents include anionic surfactantssuch as sodium dodecylbenzene sulfonate, sodium laurate, and ammoniumsalts of polyoxyethylene alkyl ether sulfate; and nonionic surfactantssuch as polyoxyethylene alkyl ether, polyoxyethylene alkyl ester,polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenylether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide, andthe like. In particular, the use of styrene-(meth)acrylic acid copolymeris preferable from the perspective of increasing pigment dispersionstability.

The oil based ink composition that is used in this aspect can alsocontain other additives which are normally added to oil based inkcompositions. Examples of these additives include stabilizers (such asantioxidants or ultraviolet light absorbers).

Examples of antioxidants include BHA (2,3-butyl-4-oxyanisole) and BHT(2,6-di-t-butyl-p-creosol), and examples of ultraviolet light absorbersinclude benzophenone based compounds, and benzotriazole based compounds.

The oil based ink composition can be prepared by a commonly known andused method. For example, if a pigment is used as the colorant, firstthe pigment, dispersing agent, and (a part of) the aforementioned blendof diethylene glycol compound and dipropylene glycol compound are mixedtogether, and then a pigment dispersion is prepared using a bowl mill,bead mill, ultrasonic waves, or jet mill or the like, in order toachieve the desired ink characteristics. Next, an oil based pigment inkcomposition can be obtained by adding a binder resin, the aforementionedblend of diethylene glycol compound and dipropylene glycol compound(remainder), and other additives (such as dispersion assisting agentsand viscosity adjusting agents) while mixing. Furthermore, a pigment anda dye can be used together as the colorant, and the oil based inkcomposition can be obtained by a similar method as the method ofpreparing the oil based pigment ink composition.

This aspect can provide the aforementioned ink set as an ink containerthat contains the chromatic color ink compositions.

Inkjet Printing Method

The inkjet recording method of this aspect forms an image using theaforementioned ink set using the inkjet recording method by driving aninkjet head, ejecting droplets of the ink composition, and causing thedroplets to adhere to the recording medium.

If the oil based ink composition that includes a metallic pigment isused individually, an image can be formed with a metallic gloss wherethe degree of mirror surface gloss measured at 20°, 60°, and 85° is noless than 200, 200, and 100 respectively, as measured in accordance withJIS Z 8741. By using this oil based ink composition, an image can beformed with the desired metallic gloss, ranging from a matte finish to agloss finish.

Specifically, if an image is formed which has measured values for thedegree of mirror surface gloss on the recording medium at angles of 20°,60°, and 85° as defined by JIS Z 8741 are simultaneously not less than200 but less than 400, 200 or higher but less than 400, and 100 orhigher, respectively, the image can have a metallic gloss that is a flatgloss finish (matte finish).

Furthermore, an image which has measured values for the degree of mirrorsurface gloss on the recording medium at angles of 20°, 60°, and 85° asdefined by JIS Z 8741 are simultaneously not less than 400 but less than600, 400 or higher but less than 600, and 100 or higher, respectively,can have a metallic gloss that has some shine to the degree that anobject reflected in the image that is formed will be somewhatdistinguishable.

Furthermore, a metallic glossy image with measured values for the degreeof mirror surface gloss at angles of 20°, 60°, and 85° as defined by JISZ 8741 are simultaneously 600 or higher, 600 or higher, and 100 orhigher, respectively, will be sharp, and can have a metallic gloss thathas so-called “mirror surface shine” to the degree that an objectreflected in the image that is formed will be clearly distinguishable.

The oil based ink composition containing a metallic pigment, and the oilbased ink composition containing the chromatic color ink composition,the black ink composition, and the white ink composition can besimultaneously ejected to form an image. Thereby, a colored metallicfinish can be provided to a colored finish of chromatic color pigment,black pigment, and white pigment.

If the oil based ink composition containing the metallic pigment and theoil based ink compositions such as the chromatic color ink composition,black ink composition, and white ink composition are ejected separately,the image is preferably formed by using the oil based ink compositioncontaining metallic pigment to form an image with a metallic gloss, andthen forming an image using the chromatic color ink compositions. Themetallic pigment will not easily penetrate into an ink receptor layerregardless of whether or not the recording medium has an ink receptorlayer, but will be attached to the surface of the recording medium. Incontrast, the pigment that is included in the chromatic color inkcomposition will easily penetrate into an ink receptor layer if ejectedonto a recording medium which has an ink receptor layer. Therefore, ifthe oil based ink composition containing metallic pigment is ejected toform an adhesive layer of metallic pigment on the recording medium, andthen the pigment of the colored ink is made to adhere thereon, the colorof the pigment of the color ink composition will be more vivid.

Furthermore, an image with metallic gloss can be formed using the oilbased ink composition containing a metallic pigment, then forming animage with a metallic gloss of any color using the chromatic color inkcomposition, and then forming an image using the black ink compositionand/or the white ink composition.

The method described below is suggested as a method for ejecting the inkcomposition.

A first method is an electrostatic aspiration method, and is a system ofapplying a strong electric field between a nozzle and an accelerationelectrode placed in front of the nozzle, continuously ejecting dropletsof ink from the nozzle, and while the ink droplets are traveling betweenthe deflecting electrodes, applying a printing information signal to thedeflecting electrode, and recording, or a system of ejecting inkdroplets corresponding to the printing information signal withoutdeflection.

A second method is a method that of forcefully ejecting ink droplets bymechanically vibrating the nozzle using a water crystal oscillator whileapplying pressure on the ink solution using a small pump. The inkdroplets that are ejected are electrically charged while being ejected,a printing information signal is applied to a deflecting electrode whilethe ink droplets are traveling between the deflection electrodes.

A third method is a system that uses a piezoelectric element, whererecording is performed by simultaneously applying pressure and printinginformation signal to the ink solution using a piezoelectric element,ejecting the ink droplets.

A fourth method is a method where the ink solution is suddenly expandedin volume by the effect of thermal energy, and uses a system whererecording is performed by heating an ink solution to form bubbles usingan ultrasmall electrode in accordance with a printing informationsignal, and ejecting the ink droplets.

Any of the aforementioned methods can be used with the inkjet recordingmethod of this embodiment, but the method of ejecting the inkcomposition without heating is preferable from the perspective ofprinting at high speed. In other words, the first method, second method,or third method are preferably used.

The recording medium is not particularly restricted, and for example,various types of recording media can be used, such as normal paper,special inkjet paper (matte paper, glossy paper), glass, plastic filmsuch as polyvinylchloride, film where a substrate is coated with aplastic or receptive layer, metal, and printed circuit boards and thelike.

If the recording medium has an ink receptive layer, the recording mediumis preferably printed without heating, from the perspective of avoidingheat damage.

On the other hand, from the perspective of achieving a high gloss, ifthe recording medium does not has an ink receptive layer, the recordingmedium is preferably heated and printed.

The method of heating can be a method of heating by bringing therecording medium into contact with a heating source, or irradiating withinfrared rays or microwaves (electromagnetic waves with extremely largewave length of approximately 2,450 MHz) or the like, or heating byblowing hot air without contacting the recording medium, and the like.

The heating is preferably performed prior to printing and/or duringprinting and/or after printing. In other words, the recording medium canbe heated prior to printing, at the same time as printing, or afterprinting, and heating can be performed throughout the printing process.The heating temperature is dependent on the type of recording medium,but is preferably between 30 and 80° C., more preferably between 40 and60° C.

Recording Device

The inkjet recording device of this aspect forms an image using theaforementioned ink set by ejecting droplets of the ink composition, andcausing the droplets to adhere to the recording medium.

Recorded Matter

The recorded matter of this aspect is recorded using the aforementionedink set, the aforementioned inkjet recording method, and theaforementioned inkjet recording device. The recorded matter is obtainedby the inkjet recording method using the aforementioned ink set, andtherefore recorded matter can be obtained which has an image with ametallic finish in any arbitrary color.

Embodiments

1. Metallic Ink Composition

(1) Preparation of Metallic Pigment Dispersion

A resin coating solution containing 3.0 wt % of cellulose acetatebuterate (butylation ratio between 35 and 39%, manufactured by KantoChemical Co., Inc.) and 97 wt % diethylene glycol diethyl ether(manufactured by Nippon Nyukazai Co., Ltd.) was uniformly applied by abar coating method onto a 100 μm thick PET film, and then dried for 10minutes at 60° C. to form a thin resin film on a PET film.

Next, an aluminum vapor deposition layer with an average thickness of 20nm was formed on the aforementioned resin layer using a vacuumdeposition device (vacuum deposition device model VE-1010 manufacturedby Vacuum Device Co.).

Next, the multilayer body formed by the aforementioned method issimultaneously peeled, pulverized, and dispersed in the diethyleneglycol diethyl ether using a VS-150 ultrasonic disperser (manufacturedby As One Corp.), and a metallic pigment dispersion was formed byultrasonically dispersing for 12 cumulative hours.

The metallic pigment dispersion that was obtained was filtered using anSUS mesh filter with 5 μm openings to remove the coarse particles. Next,the filtrate was poured into a round bottomed flask and the diethyleneglycol diethyl ether was distilled off using a rotary evaporator.Thereby the metallic pigment dispersion was concentrated, and later theconcentration of the metallic pigment dispersion was adjusted to obtaina metallic pigment dispersion 1 with a concentration of 5 wt %.

Furthermore, metallic pigment dispersions 2, 3 were prepared usingmetallic pigment where the vapor deposition conditions and/or theultrasonic dispersing time were changed.

Furthermore, 50% average particle diameter R50 of a corresponding circlein the longitudinal diameter (X direction)-lateral diameter (Ydirection) plane of each of the metallic pigments and the averagethickness Z were measured using a particle diameter and graindistribution analyzer (FPIA-3000S manufactured by Sysmex Corp.), andR50/Z was calculated based on the measurement values obtained for R50and Z. The results are shown in Table 1.

TABLE 1 Metallic 50% average Average film pigment particle diameterthickness dispersion R50 (μm) Z (μm) R50/Z 1 1.03 0.02 51.5 2 1.13 0.0256.5 3 0.86 0.02 43.0

(2) Preparation of the Metallic Ink Composition

Metallic pigment ink compositions were prepared according to theformulations shown in Table 2 and Table 3 using the metallic pigmentdispersion that was prepared by the aforementioned method. Afterblending and dissolving the solvent and additives to make the inksolvent, the metallic pigment dispersion was added to the ink solvent,and then blended and stirred using a magnetic stirrer for 30 minutes atambient temperature and pressure to make metallic pigment inkcompositions (S1 through S7).

The diethylene glycol diethyl ether (DEGDE) and the tetraethylene glycoldimethyl ether (TEGDM) shown in Table 2 and Table 3 were manufacture byNippon Nyukazai Co. Ltd. Furthermore, the γ-butyrolactone wasmanufactured by Kanto Chemical Co. Inc. In addition, the N-2043-AF-1,and N-2043-60MEX (polyacryl polyol resin emulsion) are manufactured byHarima Chemical Co. Inc., the IB-F370 (polyurethane resin) wasmanufactured by Sanyo Chemical Co., Ltd., and the BYK-3500 (surfactant)was manufactured by BYK Chemie Japan. Note, the units are in wt %.

TABLE 2 Metallic ink composition Ink composition S1 S2 DEGDE 47.8 61.8DPGMB 45 γ-butyrolactone 15 TEGDM 18 N-2043-AF-1 6.0 4.0 BYK-3500 0.20.2 Pigment solid content 1.0 1.0 (metallic pigment (1) (2) dispersion)

Metallic ink composition Ink Composition S3 S4 S5 S6 S7 DEGDE 61.8 61.057.8 61.3 60.8 γ-butyrolactone 15.0 15.0 15.0 15.0 15.0 TEGDM 18.0 18.018.0 18.0 18.0 N-2043-60MEX 4.0 4.0 — 4.0 4.0 IB-F370 — — 6.0 — —BYK-3500 0.2 — 0.2 0.2 0.2 E-1010 — 1.0 — — — Pigment solid 1.0 1.0 1.01.5 2.0 content (%) Metallic pigment 2 2 2 3 3 dispersion

2. Color Ink Composition

(1) Formulation of Color Ink Composition

A yellow ink composition, magenta ink composition, light magenta inkcomposition, cyan ink composition, light cyan ink composition, black inkcomposition, and white ink composition were prepared according to theformulations shown in Table 4 and Table 5. Note, the “dispersing agent”was a polyester based polymer compound, “N-2043-AF-1” and “N-2043-60MEX”was in a polyacryl polyol resin emulsion, the “solvent blend” was ablend of diethylene glycol diethyl ether (70 wt %) and γ-butyrolactone(15 wt %), and tetraethylene glycol dimethyl ether (15 wt %).Furthermore, the values shown in Table 4 and Table 5 are in units of wt%.

TABLE 4 Light Light Yellow Magenta magenta Cyan cyan Black White Inkcomponent Y1 M2 LM3 C4 LC5 B6 W7 W8 PY151 4 PR122 4 1 PB 15:3 3 0.8Carbon black 4 Titanium dioxide 5 Hollow resin emulsion 5 Dispersingagent 2.5 2 0.5 2 0.5 2 3 — Polyoxyethylene derivative 2 2 0.5 2 0.4 2 —— N-2043-AF-1 2.0 2.0 3.0 2.0 3.0 2.0 4.0 5.0 Organic solvent blendBalance Balance Balance Balance Balance Balance Balance Balance

TABLE 5 Ink Color ink composition complement Y9 M10 C11 B12 W13 PY2136.0 PV19 6.0 PB 15:3 3.0 PBk7 4.0 Hollow resin 10.0  emulsion Dispersing2.0 3.0 2.0 2.0 — agent N-2043-60MEX 4.0 4.0 4.0 4.0 5.0 BYK-3500 0.20.2 0.2 0.2 0.2 Organic Balance Balance Balance Balance Balance solventblend

(2) Preparation Method for Ink Compositions

Of the aforementioned formulation components, the pigment, dispersingagent, and solvent blend (a portion) were mixed for 1 hour at 3000 rpmusing a dissolver, and then preliminarily dispersed in a bead millfilled with zirconia beads (2 mm). The average of particle size of thepigment particles obtained by this preliminary dispersion was 5 μm orless. Next, full dispersing was performed using a nanomill filled withzirconia beads (0.3 mm) to obtain the pigment dispersion. The averageparticle size of the pigment particles obtained by this full dispersionwas between 50 nm and 200 nm, depending on the type of pigment.

While mixing the pigment dispersion obtained at 4000 rpm, N-2043-AF-1,normal additives, polyoxyethylene derivative, hollow resin emulsion, andorganic solvent blend (remainder) were added, the pigment weight wasadjusted to make the wt % shown for the composition in order to obtainthe desired color ink composition (Y1 through W8).

The desired color ink compositions (Y9 through W13) were obtained in asimilar manner.

Note, the aforementioned hollow resin emulsion was manufactured as shownbelow.

(a) Polymer Particle 1

80 parts of styrene, 5 parts of methacrylic acid, 15 parts of methylmethacrylate, 1 part of α-methylstyrene dimer, 14 parts oft-dodecylmercaptan, 0.8 parts of sodium dodecylbenzene sulfonate, 1.0part of potassium persulfate, and 200 parts of water were placed in a 2L reaction vessel, and while mixing under a nitrogen gas environment,the temperature was increased to 80° C. and emulsion polymerization wasperformed for 6 hours. The polymer particles 1 obtained thereby had anaverage particle size of 150 nm (0.15 μm).

(b) Hollow Polymer Fine Particle Emulsion 1

10 parts (calculated as solid content) of the polymer particles 1obtained in item (a) was combined with 0.3 parts of sodium laurylsulfate, 0.5 parts of potassium persulfate, and 400 parts of water in areaction vessel and then a cross-linking polymeric monomer compositioncontaining 11.6 parts of divinyl benzene (purity 55 wt %, remainder ismonofunctional vinylmonomer) 8.4 parts of ethyl vinylbenzene, 5 parts ofacrylic acid, and 75 parts of methyl methacrylate was added and mixedfor 1 hour at 30° C., and then emulsion polymerization was performedwhile mixing for 5 hours at 70° C. to obtain an aqueous dispersion. Whenthe product obtained was measured using a particle analyzer (MicrotrackUPA: Nikkiso Co., Ltd.), the particle size was 320 nm, and when observedunder a transmission type electron microscope, hollow polymer fineparticles were observed.

3. Ink Set

Ink sets were prepared by combining the ink compositions obtained in 1and 2 above, using the combinations shown in Table 6 and Table 7.

TABLE 6 Ink set component Metallic ink Colored ink Black ink White ink AS1 Y1, M2, LM3, — — C4, LC5 B S2 Y1, M2, LM3, — — C4, LC6 C S1 Y1, M2,LM3, B6 W7 C4, LC5 D S2 Y1, M2, LM3, B6 W8 C4, LC5 E S2 Y1, M2, LM3, B6W7 C4, LC5 F S1 Y1, M2, LM3, B6 W8 C4, LC5 G S2 Y1, M2, C4 B6 W7

TABLE 7 Ink set component Metallic ink Colored ink Black ink White ink HS3 Y9, M10, C11 B12 W13 I S4 Y9, M10, C11 B12 W13 J S5 Y9, M10, C11 B12W13 K S6 Y9, M10, C11 B12 W13 L S7 Y9, M10, C11 B12 W13

4. Printing Evaluation Test

(1) Printing Evaluation Test 1

Two inkjet printers SJ-540 manufactured by Roland D. G. were used withthe ink sets shown in 3 above. The ink compositions corresponding toeach of the color systems was added to one inkjet printer, or in otherwords the black ink composition, yellow ink composition, magenta inkcomposition, cyan ink composition, light magenta ink composition, andlight cyan ink composition were added to the yellow system, magentasystem, cyan system, light magenta system, and light cyan system,respectively. The metallic ink composition was added to the black systemand the white ink composition was added to the yellow system of thesecond inkjet printer. The heating temperature for both of the inkjetprinters was 50° C., and printing was performed using the printingpattern shown below. A vinyl chloride sheet (Viewcal 2000 (white):product of Sakurai Co. Ltd.), a PET film (PG-50L: product of LamiCorporation Inc.), and a polycarbonate film (lupilon FE-2000: MitsubishiEngineering Plastics Corporation) cut to A4 size were used as therecording medium. Furthermore, functional evaluation of the printedmatter was based on the following evaluation standard. The results areshown in Table 8.

-   AAA: Any metallic finish from high metallic gloss to matte finish    can be obtained.-   AA: A metallic finish gloss was obtained where a reflected object    could clearly be identified-   A: A metallic finish gloss was obtained where a reflected object    could barely be identified-   B: A flat finish metallic gloss was obtained (matte finish)-   C: A glossy metallic finish could not be obtained

The printing patterns using the aforementioned ink set were as shownbelow.

Printing Pattern 1

Printing was performed by ejecting each of the ink compositionsimultaneously.

Printing Pattern 2

Printing was performed by ejecting the metallic ink compositions, andthen printing was performed by ejecting the chromatic color inkcomposition and the black ink composition. In this case, the gloss couldbe masked by printing the black ink composition over the metallic print.

c. Printing Pattern 3

Printing was performed by ejecting the metallic ink compositions, andthen printing was performed by ejecting the chromatic color inkcomposition, and finally printing was performed by ejecting the whiteink composition and the black ink composition. In this case, the glosscould be changed to a matte finish by printing the white ink compositionover the glossy metallic print.

TABLE 8 Printing Pattern Ink set 1 2 3 Embodiment 1 A B A — Embodiment 2B A AA — Embodiment 3 C B A A Embodiment 4 D A AA AA Embodiment 5 E A AAAA Embodiment 6 F B A A Embodiment 7 G A A AA

(2) Printing Evaluation Test 2

Using two inkjet printers PM-4000PX (product of Seiko Epson) containinga metallic ink composition S1 and an ink set that combines theaforementioned oil based ink compositions, the black ink composition,yellow ink composition, magenta ink composition, cyan ink composition,light magenta ink composition, and light cyan ink composition were addedto the corresponding color systems of the first inkjet printer. Themetallic ink composition S1 was added to the black system of the secondinkjet printer. The white ink composition was added to the yellowsystem.

Furthermore, printing was performed according to the aforementionedprinting patterns at ambient temperature onto glossy photographic paperwith an ink receptor layer, (manufactured by Seiko Epson, productnumber: KA450PSK). Similarly, printing was performed in the same mannerusing the metallic ink composition S2 in place of the metallic inkcomposition S1. Furthermore, functional evaluation of the printed matterwas based on the above evaluation standard. The results are shown inTable 9.

TABLE 9 Printing Pattern Ink set 1 2 3 Embodiment 8 A A A — Embodiment 9B AA AA — Embodiment 10 C A A A Embodiment 11 D AA AA AAA Embodiment 12E AA AA AAA Embodiment 13 F A A A Embodiment 14 G A A AAA

As shown in Table 9, recorded matter with a metallic finish image in anarbitrary color could be achieved using the inkjet printing method andthe ink set described above.

(3) Printing Evaluation Test 3

Printed matter was obtained in a manner similar to the printingevaluation test 1 shown in 4 (1), and a functional evaluation of theprinted matter was similarly performed based on the same evaluationcriteria. The results are shown in Table 10.

TABLE 10 Printing Pattern Ink set 1 2 3 Embodiment 15 H AA AA AAAEmbodiment 16 I A A AA Embodiment 17 J A A AA Embodiment 18 K AA AA AAAEmbodiment 19 L A A A

(4) Printing Evaluation Test 4

Printed matter was obtained in a manner similar to the printingevaluation test 2 shown in 4 (2), and a functional evaluation of theprinted matter was performed based on the same evaluation criteria. Theresults are shown in Table 11.

TABLE 11 Printing Pattern Ink set 1 2 3 Embodiment 20 H AA AA AAAEmbodiment 21 I AA AA AAA Embodiment 22 J AA AA AAA Embodiment 23 K AAAA AAA Embodiment 24 L A A A

As shown in Table 11, recorded matter with a metallic finish image in anarbitrary color could be achieved using the inkjet printing method andthe ink set described above.

1. An ink set, comprising: an oil based ink composition containing ametallic pigment; and at least one or more oil based ink compositionsselected from a group consisting of a chromatic color ink compositioncontaining chromatic color pigment, a black ink composition containingblack pigment, and a white ink composition containing white pigment. 2.The ink set according to claim 1, wherein the metallic pigment is aplate-like particle, where, on a planar surface of the plate-likeparticle, a longitudinal diameter is X, a lateral diameter is Y, and athickness is Z, a 50% average particle diameter R50 which is thediameter of a corresponding circle determined by a surface area in theX-Y plane of the plate-like particle is between 0.5 and 3 μm, andR50/Z>5 is satisfied.
 3. The ink set according to claim 1, wherein themetal pigment is aluminum or an aluminum alloy.
 4. The ink set accordingto claim 1, wherein the metal pigment is made by crushing a metaldeposition film.
 5. The ink set according to claim 1, wherein an oilbased ink composition containing the metallic pigment contains themetallic pigment, an organic solvent, and a resin.
 6. The ink setaccording to claim 1, wherein concentration of the pigment in the oilbased ink composition is between 0.1 and 10.0 wt %.
 7. The ink setaccording to claim 5, wherein the organic solvent includes one or moretype of alkylene glycol ether that is a liquid at ambient temperatureand pressure.
 8. The ink set according to claim 5, wherein the organicsolvent is a mixture of an alkylene glycol diether, an alkylene glycolmonoether, and a lactone.
 9. The ink set according to claim 5, whereinthe resin is at least one type of resin selected from a group consistingof polyvinyl butyral, cellulose acetatobutyrate, and polyacryl polyol,polyurethane, vinylchloride-vinylacetate copolymer and/or a resinemulsion thereof.
 10. The ink set according to claim 5, wherein the oilbased ink composition further comprises at least one type of acetyleneglycol based surfactant and/or silicone based surfactant.
 11. The inkset according to claim 1, wherein the chromatic color pigment is anorganic pigment, the black pigment is carbon black, and the whitepigment is titanium dioxide and/or a hollow resin emulsion.
 12. An inkcontainer containing the ink set according to claim
 1. 13. An inkjetrecording method, comprising: ejecting droplets of ink composition andcausing the droplets to adhere to a recording medium, an image beingformed using the ink set according to claim
 1. 14. The ink jet recordingmethod according to claim 13, comprising: forming an image bysimultaneously ejecting the oil based ink composition containingmetallic pigment, and at least one type of composition selected from agroup consisting of a chromatic color ink composition, a black inkcomposition, and a white ink composition.
 15. The inkjet recordingmethod according to claim 13, comprising: forming an image using the oilbased ink composition containing a metallic pigment, and then forming animage of any color using the chromatic color ink composition.
 16. Theinkjet recording method according to claim 13, comprising: forming animage using the oil based ink composition containing a metallic pigment,then forming an image of any color using the chromatic color inkcomposition, and then forming an image using the black ink compositionand/or the white ink composition.
 17. The inkjet recording methodaccording to claim 13, wherein the method of ejecting the inkcomposition is a non-heating method.
 18. The inkjet recording methodaccording to claim 13, wherein the recording medium is heated andprinted.
 19. The inkjet recording method according to claim 18, whereinthe heating temperature is between 30° C. and 80° C.
 20. The inkjetrecording method according to claim 19, wherein the heating is performedprior to printing and/or during printing and/or after printing.
 21. Aninkjet recording device ejecting droplets of ink composition, andcausing the droplets to adhere to a recording medium, an image beingformed using the ink set according to claim
 1. 22. Recorded matter,recorded using the inkjet printing method according to claim 13 or therecording device according to claim 21.